Tower of God

"Twenty-Fifth Bam must journey skyward in a mysterious tower if he has any chance of reuniting with his best friend Rachel, even if that means facing his own death. Using his strength, skill and wits, Bam climbs higher and higher up the Tower despite the dangers. Bam makes both allies and enemies on his quest to find Rachel; however her intentions of reconnecting with him become unclear as new revelations about their friendship reveal a much deeper, darker secret"--Amazon.